Although there are a number of opinions as to just which dragon in legend is represented by Draco, the constellation is a very important one, for one of its stars, a star named Thuban, was at one time our Pole Star. Indeed, in 2300 B. C. the Pharaohs of Egypt looked up at Thuban as their Pole Star. As their Pole Star! But where was our faithful North Star during 2300 B. C., and how could our earth's pole swing from this point in the heavens to one half the way between the "Guards" on the tiny bowl of the Little Dipper, and Mizar on the crook of the handle of the Big Dipper? This strange phenomenon not only happened but happens regularly, for the earth "reels like a top" as well as "whirls," although the reeling motion is so much slower than the whirling motion that while it whirls once on its axis in a day, it reels around only once in 25,000 years. During this time the earth's axis describes a circle from Thuban, through the present Pole Star, around through Vega and back again. Vega may be easily located for it crosses the zenith in the late evenings of summer, a beautiful bluish-white star of the first magnitude. It will be about 11,500 years or about 13,500 A. D. before this blue star will again shine above the northern pole of our earth.
It was not an uncommon thing in olden times to build temples dedicated to the observation of certain stars. It is believed that the great pyramid of Cheops, built 4600 years ago, was so constructed that the light of Thuban, then the Pole Star, would shine down its great stone tube at the time the star was at its lower culmination. Olcott in "Starlore of All Ages" tells us that the idea was to conduct the ray of light from Thuban through the passage opening high up in the side of the pyramid, to the eye of a god hidden far down beneath its foundations. When viewed from the bottom of the tunnel, which ends in a room hollowed out of solid stone, it is said that the mouth appears but little larger than the moon's diameter. It is interesting to note that the pyramid of Cheops is the mightiest structure the world has ever seen. According to Herodotus, 100,000 men were employed constantly on this work for 20 years. But the rays of Thuban can no longer shine down the 380 feet of stone tube to light the eye of the god hidden in its depths, for the reeling of the earth has caused the tube to be out of the star's line of light. It may happen again in 21,000 years, however—if the pyramid is still there.
In China there is an observatory 4000 years old which Samuel G. Bayne in his little book the "Pith of Astronomy" speaks of visiting. Here is a slanting granite wall in which two eyeholes had been bored for the sole purpose of sighting Thuban.
Changes in the universe are very gradual and although 4000 years seems a long time to the limited mind of a human being, it is but little in comparison to the vast periods of time which must pass before a visible change can be noticed in the heavens. We speak of these years nonchalantly, but astronomers have had to work hard and patiently in order to make such assertions and to back them up with sufficient proof.
Traveling backward in imagination on the circle that our pole has taken 25,000 years to describe in the sky, and again imagining the star which we now see as our Pole Star as the Pole Star of that by-gone era, what a difference we find in the appearance of the earth! Herds of strange and savage animals are scattered here instead of thriving villages and cities, and man, in equally savage state, wanders about the hills and plains alone or in straggling bands.
In traveling forward 21,000 years again to the time only 4000 years ago when Thuban, on the coils of the Dragon, shone as our Pole Star, we come to comparatively recent times; civilization on our earth has made great advances, not the least of them being that it has raised its head and has noted that there are not only stars but that the stars differ from one another. Probably during this era the Chinese chose the Dragon for their national emblem.
The principal interest in the constellation of Draco is, of course, the star Thuban. It is interesting to locate this ancient Pole Star which lies on the tail of Draco, just above the handle of the Big Dipper, and reflect that this star was once the hub of the starry universe, with the Big Dipper whirling round and round it in a close circle.
